College of Behavioral & Social Sciences

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations..

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Subject: search.filters.subject.Psychology, Psychobiology

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Now showing 1 - 4 of 4
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    Error Observation in Schizophrenia
    (2009) Mann-Wrobel, Monica Constance; Blanchard, Jack J.; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Despite the pervasive and impairing nature of social difficulties in schizophrenia, the causes of these problems are not fully understood. It has been suggested that problems with cognitive functioning contribute to the social deficits of schizophrenia. However, little is known about the neural mechanisms that underlie cognitive processes directly linked to social dysfunction in schizophrenia. Recent studies of the mirror neuron system have focused on the error-related negativity (ERN), a negatively-deflected event-related brain potential that is elicited following the commission of an erroneous response. This study examined ERN activity in schizophrenia patients and psychiatrically healthy controls during performance and observation of a confederate performing a computerized flanker task. The lateralized readiness potential (LRP) allowed for a direct comparison of brain activation reflecting response readiness verses error signaling. Correlations between ERN activity during flanker observation, social cognition (i.e., theory of mind), and community social functioning were explored. Finally, correlations between verbal memory, executive functioning, and social functioning were examined and social cognition was explored as a mediator between neurocognition and social functioning. Results indicated that controls produced a robust ERN during execution of the flanker task, whereas ERN activity among patients was comparatively attenuated in amplitude. During observation, there were no significant group differences and no identifiable observation ERN; however, there was greater negative activity following error than correct trials in this condition for all participants. LRP activity did not parallel that of the ERN, supporting the differentiation of motor activity and error-related processing during observation. The only significant correlation to emerge between ERN activity and social cognition and social functioning was between occupational status and execution ERN activity among controls only. Unexpectedly, neurocognition and social functioning were negatively correlated in the patient group. Expectedly, these variables were positively correlated among controls. Therefore, regression analyses were conducted separately by group; however, neither neurocognition nor social cognition predicted a significant proportion of the variance in social functioning. Despite limitations, this research is discussed as a starting point for integrating the study of psychophysiological activity with social behavior and functioning, particularly in a clinical population with pronounced social deficits.
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    Susceptibility to Smoking and Nicotine Dependence in Schizophrenia
    (2009) Saperstein, Alice Meredith; Blanchard, Jack J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Evidence suggests that high nicotine dependence observed in schizophrenia is related to its core neuronal deficits such as abnormalities in neural synchronization and sensory gating. Some of these neuronal deficits are shown to mark schizophrenia liability, raising the possibility that the increased nicotine dependence in schizophrenia is related to its etiological factors. This study sought to investigate mechanisms of increased vulnerability to smoking and nicotine dependence in schizophrenia. The individual and interacting effects of familial vulnerability factors, neurophysiological function, and resting cortical oscillatory activity (i.e. resting EEG power) were examined. The study sample was composed of four groups including outpatients with schizophrenia, first-degree relatives of patient index probands, healthy comparison control subjects from the community, and first-degree relatives of control probands. The resulting data demonstrated a pattern of more persistent nicotine use and greater dependence among those with schizophrenia relative to non-psychiatric comparison controls. Persistent smoking was also demonstrated to be highly heritable across groups with no discernable difference in the extent to which smoking is familial in those affected or unaffected by schizophrenia. With respect to resting oscillatory activity, analyses failed to find diagnostic group differences in EEG power for the alpha, beta, and gamma frequency bands and, unlike other substances of abuse, past and present nicotine use did not have a reliable effect on power in the beta frequency band. Rather, power in the gamma frequency band was significantly associated with smoking status. Furthermore, smoking was uniquely related to neurophysiological processes in probands with schizophrenia, suggesting that smoking status should be assessed in any study of information-processing dysfunction in this population. When all putative susceptibility factors were considered together, diagnosis of schizophrenia and family history of smoking best captured what may be characterized as an underlying (i.e. neurobiological) vulnerability to nicotine dependence, rather than circumscribed indices of electrophysiological functioning. Future studies might be implemented to refine the association between smoking and indices of electrophysiological function and, importantly, relate diagnostic or electrophysiological susceptibility factors to mediating processes and observable behaviors associated with aberrant patterns of nicotine use and dependence in persons with schizophrenia.
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    Perceptual Consequences of Early-Onset Hereditary Hearing Loss in the Belgian Waterslager Canary (Serinus Canarius)
    (2006-05-30) Lauer, Amanda M; Dooling, Robert J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Belgian Waterslager canaries (BWS) are bred for a distinctive low-pitched song that includes sounds that are thought to resemble water. This strain of canary has been used in multiple neurobiological and behavioral studies of song learning. These birds have a permanent hereditary hearing loss associated with missing and abnormal hair cells. The hearing deficit develops after hatch, but is present when the birds learn their song. The manner in which these birds process complex sounds indisputably affects the content of their vocalizations; however, no studies have looked at BWS canaries' ability to detect and discriminate sounds other than detection of pure tones in quiet. Thus, the BWS canary provides a unique opportunity to investigate the relationship between the form and function of an auditory system involved in vocal learning. Here I describe a series of psychoacoustic experiments that investigate differences in masking, discrimination, temporal processing, and perception of song elements in BWS canaries and normal-hearing non-BWS canary strains. Spectral and temporal studies of masking showed that frequency resolution and the phase response of the basilar papilla are impaired in BWS canaries. Frequency discrimination was superb at low frequencies, but worse than normal at high frequencies in BWS canaries. Duration and intensity discrimination was not adversely affected by the hearing loss. Temporal resolution was normal or better than normal under some conditions in BWS canaries. Despite the hearing loss, BWS canaries are able to accurately discriminate among strain-specific song syllables as well as syllables of other canary strains. In fact, BWS canaries are actually better than non-BWS canaries at discriminating among BWS canary syllables. These perceptual predispositions in BWS canaries are presumably related to the structural abnormalities of the inner ear, and are likely to play a role in song learning and song maintanence by enhancing the birds' ability to attend to important acoustic features that are characteristic of BWS vocalizations.
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    Spatial Contrast Sensitivity of Birds
    (2003-12-05) Ghim, Mimi M; Hodos, William; Psychology
    Contrast sensitivity (CS) is the ability of the observer to discriminate between adjacent stimuli on the basis of their differences in relative luminosity (contrast) rather than their absolute luminances. Prior to this study, birds had been thought to have low contrast detection thresholds relative to mammals and fishes. This was a surprising phenomenon because birds had been traditionally attributed with superior vision. In addition, the low CS of birds could not be explained by retinal or optical factors, or secondary stimulus characteristics. Unfortunately, avian contrast sensitivity functions (CSFs) were sparse in the literature, so it was unknown whether low contrast sensitivity was a general phenomenon in birds. This study measured CS in six species of birds sampled across different taxa and different ecological backgrounds in order to answer this very question. The species chosen for this experiment were American kestrels (Falco sparverius), Barn owls (Tyto alba), Japanese quail (Coturnix coturnix japonica), White Carneaux Pigeons (Columba livia), Starlings (Sturnus vulgaris), and Red-bellied woodpeckers (Melanerpes carolinus). CSFs were obtained from these birds using the pattern electroretinogram (PERG), and compared with CSFs from the literature. The quail and pigeon data obtained in this experiment fit well with existing CS data for these species. The kestrel data were not similar to kestrel data in the literature; however the data in the literature were collected from a single subject. All of the birds studied had contrast sensitivities that were consistent with their retinal or optical morphologies relative to other birds (in species for which such data exists) and seem well suited for their natural environments. In addition, all of these birds exhibited low CS relative to humans and most mammals, which suggests that low CS is a general phenomenon of birds. Explanations for this avian low CS phenomenon include a possible trade-off between contrast mechanisms and UV mechanisms in cone systems, and lateral inhibitory mechanisms that are perhaps categorically different from mammals. Lateral inhibition affects contrast gain, and has been shown to differ according to ganglion cell types, which in turn will differ in vertebrate species.